Technical Field
The present invention relates to transistor fabrication and, more particularly, to the fabrication of transistors with thinned channel fins.
Description of the Related Art
Limits on length of gates in fin field effect transistors (FinFETs) are imposed by fin width. As the gate length decreases, short channel current leakage increases. Because new technologies are capable of forming progressively smaller transistors, these short channel effects become significant challenges in transistor design. Forming transistors with thinner fins helps enhance gate control over the transistor channel, thereby reducing current leakage.
However, uniformly decreasing the size of fins presents its own challenges. When the width of a fin is reduced, current crowding at the fin's exterior increases. This increases the effective resistance of the thinner fin, which impacts the drive current performance of the FinFET. This compromises the benefits to the subthreshold leakage control provided by having a thinner fin.
Existing processes for thinning fins include oxidation. However, such thinning processes may undercut spacers around the channel region, resulting in physical faults or defects in the resulting transistors. As such, existing oxidation processes are inadequate for producing small-scale devices.